PCBP4 (poly(rC) binding protein 4) is an RNA-binding protein that preferentially binds oligo dC sequences and regulates mRNA stability through 3'-UTR interactions. Primary functions include regulation of cell cycle progression and apoptosis, predominantly through post-transcriptional control of key cell cycle regulators. PCBP4 negatively regulates p21 mRNA stability 1 and positively regulates ZFP871 mRNA stability, which in turn promotes p53 degradation via proteasome-dependent mechanisms 2. PCBP4 also induces G2/M cell cycle arrest and mediates cisplatin resistance in cancer cells through suppression of Cdc25A expression 3. Clinically, PCBP4 functions as a tumor suppressor; PCBP4-deficient mice develop lung adenocarcinoma, lymphoma, and kidney tumors with reduced p53 expression 2. Conversely, PCBP4 suppression enhances cisplatin sensitivity in resistant head and neck cancer cells 3. PCBP4 expression is dysregulated in response to DNA damage and during cancer treatment, with altered expression associated with apoptosis and cell cycle arrest genes 4, 5. Notably, PCBP4 has been identified as a molecular predictor of resistance to anti-MDK (midkine) therapy in glioblastoma 6. Additionally, genetic variants in the PCBP4 promoter region show suggestive association with severe diabetic retinopathy in type 1 diabetes 7.